1. Field of the Invention
The present invention relates to a landing position measuring apparatus and a landing position measuring method for measuring the landing position of ink ejected from an inkjet print head.
2. Description of the Related Art
An inkjet print head fabricating process includes an inspecting process for evaluating whether or not ink ejected from an ejection port formed at an inkjet print head fabricated is landed at an accurate position on a print medium. A method in the inspecting process disclosed in, for example, Japanese Patent Laid-Open No. H04-336273(1992) has been known. With this method, an inspection pattern is printed in such a manner that droplets ejected from a plurality of ejection ports do not overlap each other, thereby measuring the position of gravity of each of dots. The quality of a print head is evaluated based on the uniformity of the landing position with reference to the position of gravity as a dot landing position.
The above-described ink droplet landing inspection pattern disclosed in Japanese Patent Laid-Open No. H04-336273(1992) is adapted to evaluate the quality with reference to a single dot. However, in a case where the volume of a droplet to be ejected is small, a difference in area of a landed dot is small between a dot of a main droplet to be ejected and a dot of a satellite droplet to be sequentially ejected in a small quantity with a delay from the ejection of the main droplet. As a consequence, it may be difficult to determine whether the droplet is a main droplet or a satellite droplet in the ink droplet landing inspection pattern consisting of a single dot when a camera captures a droplet.
In view of the above, there is a method in which a print head is moved by a designated amount in a scanning direction while ejecting a plurality of ink droplets from ejection ports so as to form one pattern. The landing position of a droplet may be accidentally shifted due to an increased viscosity of ink or the like at the beginning of the ejection. To cope with this shift, it is necessary to eject droplets from one ejection port a plurality of times so as to form a pattern, thus complementing a landing position shift.
However, in ejecting droplets from one ejection port a plurality of times so as to form one pattern, such a pattern may be possibly broken caused by accidental deficient ejection or a flaw or smear on a sheet in the middle of the pattern. If the pattern broken in such a manner is inspected as it is, the pattern may be erroneously recognized, thereby raising a problem of abnormal evaluation or inspection.